In the Garden:
Lower South
June, 2012
Regional Report

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These young leaffooted bugs lack wings to fly away, making them easier to control before they do significant damage to our tomato fruit.

Fending Off Tomato Pests & Diseases: Part II

In pursuit of a bountiful harvest of fresh garden tomatoes, we encounter a number of pests and diseases that share our fondness for this wonderful garden plant. My previous report focused on a number of these pests and I'll continue this time with more of the "usual suspects" that often show up to spoil the show.

Stinkbugs and Leaffooted Bugs
Stinkbugs and their cousins, the leaffooted bugs, are among the biggest challenges to a harvest of top quality fruit. Like other true bugs, these insects have piercing-sucking mouthparts with which they do unspeakable things to our beloved tomato fruits. (Warning: the following is not for easily queasy reader!) These table-manner-challenged bugs puncture OUR tomatoes with their mouthparts and then "spit" a caustic substance that dissolves cells around the area. Then they slurp up the contents, move over a few steps and puncture another spot. The results are white to light yellowish hard spots on the fruit that can make it unfit for the table, especially now that you know what those spots you've been seeing really are!

These bugs are not as easily controlled as most other garden pests. There are few simple and effective organic options or even synthetic sprays labeled for use on tomatoes for stink bug control. Options for controlling these plant-feeding bugs include hand removal, spraying, and trap crops.

If you can learn to identify the egg clusters of these pests, it is possible to remove a large group of these bugs with a thumb and forefinger before they have a chance to hatch. After hatching, the young nymphs tend to stick together in a mini "herd" making it easy to smash them or if you're squeamish, to pick a leaf and toss it in a container of soapy water and then remove them from the garden. Both stink bugs and leaffooted bugs leave a foul odor on your hands so you may want to wear some plastic gloves. Although hand picking may sound tedious, unless you have a lot of tomato plants it is not that difficult to give the plants a "once over" once or twice a week in search of any new eggs or newly hatched nymphs.

In my previous regional report I mentioned using a vacuum to suck up these pests after they hatch and are gathered together in a group on the plant foliage. It may sound strange but it can really minimize these pests and their damage if done once or twice a week to prevent them from reaching the adult stage. I should note here that when bugs are in the nymph stage they lack wings, making them each to catch or vacuum up. Once they reach the adult stage they can fly away, making hand gathering, vacuuming, and even spraying very difficult.

If you choose to spray for these pests, keep in mind that most products are marginally effective. The dense canopy of a tomato plants create a challenge to reaching all areas where the pest may be gathered. Spraying in the early morning when the bugs are a bit more sluggish can help improve effectiveness of the spray.

A final option is to use trap crops to lure the pests away. Then the bugs can be picked, vacuumed, or sprayed while on the trap crop, leaving your tomatoes pesticide --and bug -- free. Some plants that are attractive to stink bugs and leaffooted bugs include sunflowers, pearl millet, bread seed poppy pods (after the petals fall), southern peas, cardoon and artichoke blooms, and thistle blooms. The challenge with trap crops is having the crop at the desired stage just before or about the same time as the tomatoes become a target for the bugs. With sunflowers and millet the seeds are most attractive when they are soft and developing; in the case of millet the seeds are most attractive in the "milky" stage before the firm interior of the seed starts to form.

Tomato Diseases
A number of diseases can infect our tomato plants; more than space allows in this report. Leaf spots and blights of various types are common. Not all cultivars are equally susceptible, so keep good notes on what affects your favorite ones each year. Mulch the soil to prevent rain or sprinkler irrigation from splashing soil onto the lower foliage. Avoid unnecessary wetting of the foliage by using drip rather than sprinkler irrigation. There are several organic and synthetic fungicides labeled for use on tomatoes. These should be applied before leaf diseases become rampant since the sprays work to protect against diseases, rather than to cure existing spots.

Several diseases infect the plants in the roots or at the soil line. Two wilt diseases, fusarium and verticillium, essentially clog up the "plumbing" of the plant, preventing water and nutrients from moving from the roots to the top. The result is wilting and death of plants. There is no spray for these diseases, but you can avoid them by selecting cultivars with natural resistance. Look for the letters V and F after the cultivar name for indication of such resistance. Numbers after these letters (F1F2) or double letters (FF) indicate resistance to multiple strains of the disease; even better!

Speaking of letters, you will often find other letters after the cultivar name that indicate resistance to additional problems including: T (tobacco mosaic virus), N (nematodes, a root infecting pest), A (Alternaria -- stem cankers, not early blight), TSWV (tomato spotted wilt virus), and St (Stemphylium or gray leaf spot of the foliage).

Viruses can also infect our garden tomato plants. The symptoms of viruses vary, but some of the most common show up as distorted (twisting, cupping, curling) growth at the ends of the vines, while older foliage appears normal. Insects carry the viruses, infecting the plants as they feed on them. There is no cure for tomato viruses and the plants should be pulled and removed from the garden.

Herbicide Injury
Herbicide injury can show up as symptoms similar to those of virus infection by appearing on the newest growth. There is no remedy for an herbicide injured plant. Prevention is the best approach. Avoid using the same sprayer to apply broadleaf weed killers as you use to spray pesticides in your garden. When using hay or grass clippings to mulch your tomatoes, check first to make sure no broadleaf weed killers were applied to the hayfield or lawn. Even manure from cattle that grazed on treated pastures can contain enough of the herbicide to affect tomato plants.

There are other challenges we face in our pursuit of the perfect tomato. What additional challenges have you had and what did you do about them? I invite you to visit my garden blog and share your experiences with other readers.


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